Delayed action mercury switch



July 23, 1957 F. H. HEsH 2,800,537

DELAYED ACTION MERCURY SWITCH Filed Oct. 19. 1954 F/Ezj. m?.

United States Patent O DELAYED AC'HON MERCURY SWITCH Frank H. Hesh, Chicago, Ill.

Application October 19, 1954, Serial No. 463,177

7 Claims. (Cl. 20G-33) My invention relates to a mercury switch and more specifically to a delayed action mercury switch.

Delayed action mercury switches have been the sub* ject of much development, but the switch of my invention possesses many advantages over those which I have known or seen described. My switch is delayed in its action in only one direction, obstructing adjustably the flow of the mercury in one way but permitting its unimpeded ow in the other. As will be apparent from the description following, however, the principle may be applied to provide either a delayed circuit opening or circuit closing switch. My switch is extremely simple, sure in operation, and there is virtually no way in which it can fail. It is adjustable as to the time of delay. The component parts of the switch are few in number, inexpensive and do not require a high degree of precision so that switches embodying my invention may be most inexpensively manufactured.

Other objects and advantages of my invention will be apparent from the following description and drawings, of which:

Fig. 1 is a longitudinal vertical section through a switch embodying my invention;

Fig. 2 is a rear elevation of the switch with the back wall of the switch box and a portion of the envelope broken away;

Fig. 3 is a perspective View of the envelope of my switch;

Fig. 4 is a section through the envelope and may be regdarded as being taken along the line 4 4 of Fig. 3; an

Fig. 5 is a perspective of the switch base of my invention with attached elements.

The illustrated switch consists generally of a base section and an evelope 12. The base section includes a mounting block 14 which will preferably be formed of plastic. This block may be somewhat rectangular in shape as illustrated, although the shape is not critical to its performance. At opposite edges of the mounting block metal pivot pins 16 are embedded in the block to protrude therefrom. The block has a cylindrical mounting plate 18 secured in the forward face thereof. The mounting plate has an axial internally threaded bore 20 therethrough. A threaded adjusting rod 22 is contained in the bore 20, the rod being threaded 24 in the region adjacent the bore 20. The outer end 26 of the rod extends outward from the back side of the block 14 and has a plastic button 28 secured thereto.

The block may have a recess 30 formed on the back side thereof such that the button may extend partially into the block as at 32. The recess 30 should tit rather closely the button 28, and the inside end of the button be situated on the rod so that the end of the button remains in the recess through the normal range of adjustment of the switch.

lThe plate 18 also carries a supporting arm 34 for a butterfly valve 36. The arm 34 may be secured to the Patented July 23, 1957 ICC plate 18 by soldering or some equivalent means at the upper edge of the plate 18. That end 38 of the arm carrying the butterfly valve 36 may have secured thereto a bracket 40 which should have a curved upper surface 42 to conform to the inside of the cylindrical envelope 12 but a straight horizontal lower surface 44 to provide a straight edge for hinging. To this edge, the butterfly valve 36 is secured, an ordinary hinge 46 providing the inter-connection.

The butterfly valve 36 should conform closely tothe lower inside surface of the envelope 12 and, with'the bracket 40, constitute a disk, which should be capable of performing as a nearly completely effective stopper within the inside of the envelope 12. The butterfly valve 36 should constitute substantially more than half the stopper or in other words, the line of hinging should be displaced well above the center of the envelope.

The envelope is a simple, cylindrical glass or plastic hollow cylinder closed at one end 48. A pair of contacts are embedded in the cylindrical surface of the envelope adjacent end 48 and the bottom of the envelope and extend horizontally through the wall of the envelope. A drop of mercury 52 is contained within the envelope. The other, open, end 54 of the envelope 12 enclosed the protruding edge of the plate 18 and is secured thereto by cementing, heat in the case of plastic, etc.

My switch may be incorporated in a box 55, dimensioned like and resembling generally a common outlet box with a face plate and having similar provisions for attachment to a wall, etc. A pair of vertically oriented arcuate contacts are secured at their ends to the side walls 57 of the box with insulated bolts 58. The central portions 62 of the tracks are offset inwardly toward each other and into sliding contact with the outer ends 64 of the contacts 50.

The pivot ends 16 of the base 10 will also be secured in appropriate receptacles 66 in the side walls of the box 55 to lie approximately in the same horizontal plane as the center of the tracks 56 and appropriately spaced so that the contacts 50 remain in contact with the tracks 56 throughout the range of movement of the switch.

The lower bolts 58 may have extra nuts thereon outside the box to provide terminals 60 for the circuit leads 65.

The operation of my switch will be readily understood from the foregoing description. The circuit terminals 60 are attached as illustrated to the tracks 56, the points 64 being in contact therewith. When the switch tilts downwardly to depress the right or contact end (Fig. l) the mercury globule will run down, displacing the valve easily and immediately bridging the contacts 50 to complete the circuit (Fig. 2) between the left terminal 60, the left track 56, the left contact 64, the mercury 52, the right contact 64, the right track 56 and the right terminal 60. Upon passage of the mercury drop, the butterfly valve will fall to its pre-set position against the end of the adjusting rod 22. When the position of the switch is reversed with the contact or right end raised, the mercury will tend to ow to the other end, but its flow will be inhibited by the valve 36 and, depending on the adjustment of the valve, will take a greater or less time to flow past the valve. This retarded flow, of course, means that a sutiicient quantity of mercury will be held back behind the valve to bridge the contacts for the adjustable period. The location of the valve, it will be understood, should be relatively close to the contacts so that there will be as little storage space for the mercury between the valve and the upwardly inclined bottom of the envelope 12 as possible downward of the contacts 50.

The adjusting rod, of course, extends variably into the envelope to position the valve variably away from the bottom of the envelope to adjust the rate at which mercury can flow past the valve during lthe delayed circuit opening.

It will be appreciated from the foregoing `description thatthe switch of my design can be very inexpensively fabricated. It includes very few parts and there are few precision requirements embodied in it. Likewise, the simple hinging with the abutment stop ofthe adjusting rod bearing against the valve permits free flow in one direction and restricted flow in the other direction, representing about as simple a method for accomplishing a desired end as can be imagined. The screw adjustment of the adjusting rod provides awide degree of adjustability with referenceY to the time` delay vfromvirtually instant circuit opening to an indefinitely prolonged circuit opening. For -maximum.accuracy, the adjustment, of course, will be empirical and made against the users watch, but once a desired adjustment has been made, there are no parts to move, no parts 'to wear, to alter the time interval. For approximateintervals, the abutment stop may carry calibration marks.

Itfwill further be appreciated that by virtue of the adjustment knob 28 lying normally inside the rather closely tting'recess 30, accidental contact of the operators -hand with the adjustment rod 26 is impossible, `so avoiding shock hazard.

Many Ymanufacturing alternatives are feasible in the practice of my invention. I have described the plate 18 as being embedded in the block 14. The pivots 16 could possibly be secured to the plate 18 prior to the molding of the plate in the block so that the 'pivots constitute anchors for the plate within the block. Such a circumstance could prevail where the pivots are mounted in thoroughly insulated sockets. Alternatively, the plate 18 could be secured to the face of the block in well-known fashion simply by having small, headed anchors affixed to the back surface thereof which will be embeded in the solid front face of the block. It is indeed even conceiv able that the entire base could be molded of plastic to include the elevation 18, and threads cut in the plastic itself or `a threaded metal sleeve inserted in a bore in the plastic for engagement with the adjusting rod.

Another alternative which presents itself is the possibility of employing the contacts 50 asa pivot for the switch as well as for electrical contact purposes. Such an arrangement would avoid the necessity of using the contact tracks 56 and the pivots 16 extending from the base. Should a delayed switch closing be desired-rather than'a switch opening, the contactsmay be moved to the other side of the valve 36k or the adjusting rod 22 may extend through the valve with a cross pin inthe end thereof to bear against the back of the valve to .accomplish the desired restraint of the valvein the opposite direction. v

Other alternative detailsin both manufacture and rearrangement will suggest themselves and. I therefore wish that my invention be regarded as being limited only as setforth in the following claims.

YI claim:

1.,A delayed :action mercury switch comprising a closed tube, a drop of mercury in said tube, a-pair of contacts extending through the wall of said tube adjacent onev end and the bottom thereof and spaced apartinside said tube, a valve hingedly supported adjacent the top of said tube and proportioned to block the flow of the mercury from one end to the other end `of said tube and adjustable abutment means externally operable and extending into said tube restraining the movement of said valve in one direction. A 2. The combination as set forth in 'claimv l, including vadditionally means on said tube'for mounting said switch for pivotal movement in a vertical plane. v

3. A delayed action mercury switch comprising a closed tube, a drop of mercury in said tube, a pair of contacts extending through the wall of said tube adjacent one end and the bottom thereof and spaced apart inside said tube, a valve hingedly supported adjacent the top of said tube and proportioned to block the ow of the mercury from one end to the other end of said tube and a rod extending through the other end of said tube and screw-threaded therein, said valve abutting against the inner end of said rod when said tube is tilted to iiow mercury away from said contacts, said rod being externally rotatable to adjust the abutting position of said valve.

4. A delayed action mercury switch comprising a base, an envelope secured at one end to said base, a pair of contacts adjacent the other end of said envelope adjacent the bottom and other end of said envelope extending through said envelope and spaced apart therewithin, a drop of mercury within said envelope, a valve hingedly supported adjacent the Atop of said envelope and proportioned to block the .flow of the mercury from one end rto the other end of said envelope, and adjustable abutment means vrestraining the movement of said valve in one ,direction.

5. .A delayed action mercury switch comprising a base, an envelopev secured at one end to said base, a pair of contacts adjacent the bottom and the other end of said envelope extending through said envelope and spaced apart therewith, a drop of mercury within said envelope, a valve hingedly supported adjacent the top of said envelope and proportioned to block the ow of the mercury from one end to the other .end of said envelope, and an adjustment rod screw-threaded in said base and extending into said envelope to restrain the movement of said valve in one direction, said rod `being externally adjustable.

6. A mercury switch comprising a base, means on said base for mounting said switch for pivotal movement in a vertical plane, an envelope secured at one end to said base having a drop of mercury therein, a pair of electrical contacts extending through the wall of said envelope adjacent the bottom and other end of said envelope spaced apart within said envelope, a valve support mounted on said base and extending adjacent the upper side of said envelope, a butterfly valve hingedly suspended from the end of said Yvalve support, said valve being proportioned to block the ow of mercury from one end of said tube to the other when said valve is hanging perpendicularly from said support and adjustable abutment means screwthreaded in said base and extending into said envelope adapted to'abut against said valve to prevent adjustably the full closure of vsaid valve to restrain thel ow vof mercury away from said contacts when said switch is tilted 'forsuch flow.

`7. A delayed action mercury switch comprising `a closed tube, a drop of mercury in said tube,'a pairof contacts extendingthrough rthe wall of said tube adjacent one end and the bottom thereof and spaced apart inside said tube, said contacts-.extending outwardly from the sides of said tube, a valve hingedly supported in said tube adjacent the top thereof and proportioned to block the flow of the mercury from one end to the other end of said tube, a'djustableabutment means externally operated and extending into said tube to limit the movement of said valve vin .one direction, means on said tube spaced longitudinally from said contacts supporting said tube for pivotal movement in a vertical plane, and arcuate contact tracks adapted for electrical connection mounted to provide continuous Contact with said outwardly extending contact portions .during said pivotal movement in `a vertical plane.

References Cited in the' leof this patent UNITED STATES PATENTS 1,797,974 Brandall Mar. 24, 1931 

